Agilent Technologies E1437A, Руководство пользователя, Страница: 95 / 214

In addition to controlling the progression through the four module states, the SYNC
signal is used to allow for synchronizing the decimation counters and local oscillators
of multiple E1437 modules. This is done by calling
hpe1437_filter_sync and/or
hpe1437_frequency_sync prior to asserting SYNC with hpe1437_meas_control . This
is normally done with the module in the Idle state; however, the center frequency can
also be changed in the Measure state with
hpe1437_frequency_sync if the modules
are all programmed for continuous (non-block mode) data collection.
If all modules in a multi-module system are in the Idle state when the
hpe1437_meas_control sync parameter is asserted, the LO frequency will be updated
and the next measurement will be armed. If all modules are in the measurement state in
continuous mode, the LO frequency will be synchronously updated, and the
measurement will continue. In continuous mode you should ensure that all modules are
in the same state, either the Idle state or the Measure state, before using
hpe1437_meas_control to assert SYNC. Otherwise some modules will re-arm while
others will continue the current measurement. In block mode the sync assertion will be
ignored unless all modules are in the Idle state.
The hpe1437_meas_control function assures that a single module is in a valid state by
checking that the hardware complete and sync valid bits in the status register are both
true. In synchronous multi-module systems you should use the hpe1437_wait function
for each module to assure a valid state in non-master modules within a synchronous
group.
In the case of systems made up of multiple mainframes you must be aware that only
modules in mainframe A may assert
sync . Any sync asserted in other mainframes is
ignored.
Example
The program multichan.exe described in Example Programs provides an example of
how to correctly set up a multi-module measurement using hpe1437_meas_control to
initiate state transitions.
Reset Values
idle RELEASE
sync RELEASE
Effect on Active
Measurement
This command may or may not abort any measurement in progress when any
parameter value is changed, depending on the write value.
See Also
hpe1437_init, hpe1437_status_get PAGE 56 , hpe1437_data_, hpe1437_filter_sync,
hpe1437_frequency_sync, hpe1437_clock_setup, hpe1437_wait PAGE 64
E1437A User's Guide
VXI
plug&play Programming Reference
4-48
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